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Twenty-Six-Year Monitoring of Water Masers
G.M. Rudnitskij1, M.I. Pashchenko1, V.F. Esipov1, V.A. Samodurov2, I.A. Subaev2, A.M. Tolmachev2 and E.E. Lekht1,3
1Sternberg

Astronomical Institute, Moscow State University, 13 Universitetskij prospekt, Moscow, 119992 Russia (gmr@sai.msu.ru) Russ gmr@sai.msu.ru 2Pushchino Radio Astronomy Observatory, Astrospace Center of the Lebedev Institute of Physics, Russian Academy of Sciences, Pushchino, Moscow Region, 142290 Russia (sam@prao.ru) 3Instituto Nacional de AstrofМsica, сptica y ElectrСnica, Luis Enrique Erro No. 1, Apdo Postal 51 y 216, 72840 Tonantzintla, Puebla, 1, MИxico (lekht@inaoep.mx)

Rudnitskij et al. Twenty-Six Year Monitoring of Water Masers IAU Symposium 242, Alice Springs

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Contents of the work
A sample of H2O maser emission sources has been observed since 1980. The sample includes 125 sources (65 star-forming regions and 60 late-type variable stars). The purpose of this work is to study the variability of the H2O maser emission on a long time interval. The observations are carried out on the average once per month. Since 1994 late-type stars are observed also spectroscopically to find out correlation between maser variations and optical emission lines.

Rudnitskij et al. Twenty-Six Year Monitoring of Water Masers IAU Symposium 242, Alice Springs

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Radio spectroscopy
· RT-22 radio telescope (Pushchino, Moscow Region) · Helium-cooled FET amplifier of the 1.35-cm band (TN =150­200 K) · 2048-channel autocorrelation spectrometer (velocity resolution 0.082 km/s) · Sensitivity at the 3 level about 10 Janskys
Rudnitskij et al. Twenty-Six Year Monitoring of Water Masers IAU Symposium 242, Alice Springs

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Star-forming regions
HII regions Young stellar clusters (W31) Bipolar outflows IRAS sources in cool interstellar clouds Protoplanetary discs (S255, NGC 7538 and others)

Rudnitskij et al. Twenty-Six Year Monitoring of Water Masers IAU Symposium 242, Alice Springs

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Maser in a protoplanetary disc (S255)

Flux density, Jy

S255: H2O line profile 5 February 2002

Radial velocity, LSR, km/s
Rudnitskij et al. Twenty-Six Year Monitoring of Water Masers IAU Symposium 242, Alice Springs

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Sgr B2 H2O flares
Sgr B2
13.03.1986

Flux density, Jy

1000 Jy
14.11.1986 26.12.1989 11.05.1991 23.01.1998 10.11.1998 31.03.2000 23.09.2003

22.04.2004

16.06.2004

22.07.2004 27.09.2004

Rapid variability in the H2O maser W33B 27-28 April 2006, UT 22:35:07-04:52:02 58 spectra (6.5 min exposure each)
55 60 65 70 75 80

45

50

Radial velocity VLSR , km/s

Rudnitskij et al. Twenty-Six Year Monitoring of Water Masers IAU Symposium 242, Alice Springs

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Sample H2O spectra
250 200

NGC7538
27.03.2002 10.04.2001

NGC 7538
Velocity drifts of the H2O features (chains)
NGC 7538
-57.4
1

Anticorrelation
Intrgrated flux, Jy km/s
125 100 75 50 25 0 50 40 30 20 10 0
-49.2/-45.9 -74/-69.7

250
1 2
-69.7/-64.8

(a)

200 150 100 50 0 125

Flux density, Jy

150 100 50 0

9

8
-52.2/-49.2

(b)

100 75 50 25 0

(a)
2 3 4 5 6 7 8 9 10 11 12 13 14

-70

-65

-60

-55

-50

-45

A

Radial velocity VLSR , km/s

, km/s

-57.6 -57.8 -58.0 -58.2 -58.4 100 80

B

1

125

LSR

2

Radial velocity V

Integrated H2O line flux
800

3 4

100 75 50 25 0 1996

1

9

(c)

NGC7538
.

-68.8 -60 -53.6 -53.6 -60 -60

Integrated flux, Jy km/s

600

1998

2000

2002

2004

-62 -58

15
c

Time (Years)
c

o

-55.9 km/s

-64

200

-56.5

6 5

7 9 8

11 12 10 13

North

15

Flux density, Jy

Northern component of the core of HII region

60 40 20 0 1996 1998
2b 1 2a 3 4

n
Bipolar outflow Protoplanetary disk
O O

0 1984 1988 1992 1996 2000 2004

2 9

1
O O

-59.9 -60.0 -60.1 -60.2 -60.3 -60.4

5

8

2000

2002

2004

2006

Toward observer

Turbulent vortex
1998 2000 2002 2004

Time (Years)

Southern component of the core of HII region
o

c

o

o

Rudnitskij et al. Twenty-Six Year Monitoring of Water Masers IAU Symposium 242, Alice Springs

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O
o
c
c

Model: rotating disc and bipolar outflow 7

o

400

-54.6 (N+S) -46.6

c

c

c

-64

c

(b)

o


Stellar masers
H2O
Y Cas, IK Tau, W Eri, RS Eri, R Tau, NV Aur, IRC+60154, AW Tau, IRC+60169, U Lyn, GX Mon, VY CMa, Z Pup, QX Pup, X Hya, U CVn, RU Hya, Y Lib, WX Ser, VX Sgr, IRC­10414, V1111 Oph, RW Lyr, IRC­20540, RT Aql, V391 Cyg, SY Aql, DR Cyg, NML Cyg, UU Peg, AM Cep, PZ Cas

H2O + H
R Aql, RR Aql, U Aur, RX Boo, R Cas, S CrB, R Crt, S Crt, U Her, W Hya, R Leo, R LMi, U Ori, R Peg, S Per, R Tri, RS Vir, RT Vir

Semiregular varibales underlined
Rudnitskij et al. Twenty-Six Year Monitoring of Water Masers IAU Symposium 242, Alice Springs

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Optical spectroscopy
125-cm telescope, Crimea Grating spectrograph CCD cameras, Santa Barbara Instruments Group Sensitivity in the H region: a spectrum of an 11th magnitude star can be obtained in a 10-min exposure.

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Mira-type variable R Leo, P = 310d
Optical spectrum H2O line H-H2O integrated flux

Rudnitskij et al. Twenty-Six Year Monitoring of Water Masers IAU Symposium 242, Alice Springs

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Mira-type variables S CrB and U Aur: visual light curves, H and H2O integrated fluxes
S CrB, P = 360
mvis 6 8 10 12 14
d

U Aur P = 408 mvi
8
s

d

(a)(

AFOEV)
200

10 12 14 300 200 100

F(H), -10 10 -2 erg cm s

(b)
-1

F(H), -10 1510 0 -2 -1
100

-18 logF(H2O), -19 Wm
-2

-19 -20 -21 50500 51000 51500 52000 JD-2400000 2002.0

(c)

lgF(H2O),
-2

-20 50000 1996.0 51000 1998.0 2000.0 52000 2002.0

53000 JD-2400000 2004.0

1997.0

1998.0

1999.0

2000.0

2001.0

Rudnitskij et al. Twenty-Six Year Monitoring of Water Masers IAU Symposium 242, Alice Springs

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Model: Shock wave in a mira's atmosphere

Shock 1 H

Star

Shock 2 H2O

Postshock maser shell

Rudnitskij et al. Twenty-Six Year Monitoring of Water Masers IAU Symposium 242, Alice Springs

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